1. Field of the Invention
The present invention relates to a color conversion apparatus for performing a color conversion of color data included in page information comprising image information and character information into different color data.
2. Description of the Related Art
Hitherto, in a plate making process in the printing industry, there is needs to perform a color conversion of color data included in page information for color printing into different color data, and thus various types of color conversion apparatuses meeting such needs are developed and widely used.
However, according to the former color conversion apparatus, character information included in the page information, image information, and screen tint information and gradation information which are a kind of the image information are subjected to a color conversion by the same color conversion table. Accordingly, this is associated with such a problem that a color of characters after the color conversion is insufficient in brightness, a tone of a natural image is unnatural, and a continuity of a color in an area of gradation information is damaged, so that a quality of an image is degraded.
Further, recently, with the development of a word processor software for a personal computer and a work station, and DTP (Desk Top Publishing) software, there is enhanced such a requirement that page information, which is produced by those sorts of software, is inputted to a printing machine using a printing ink to obtain a genuine printed matter. However, while the page information outputted from the word processor software and the DTP software is basically produced in form of RGB (Red, Green and Blue) color space data, the page information involved in the printing machine side is produced in form of CMYK (Cyan, Magenta, Yellow and Black) color space data for printing ink. Accordingly, in order that the page information consisting of RGB color space data produced by the word processor software and the DTP software can be dealt with in the printing machine, it is necessary to perform a color conversion for the page information consisting of RGB color space data into the page information consisting of CMYK color space data.
Also in the color conversion from the RGB color space data into the CMYK color space data, in a similar fashion to that of the above mentioned matter, character information included in the page information, image information, and screen tint information and gradation information are subjected to a color conversion by the same color conversion table. Thus, it often happens that colors of those types of information after the conversion are unsatisfactory.